JPH0560508B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an aqueous dispersion type coating composition, and more particularly to an aqueous dispersion type coating composition having excellent corrosion resistance, storage stability, and good finished appearance. [Conventional technology] In recent years, even in the general industrial painting field, where electrodeposition coating systems have not been adopted from the viewpoint of environmental protection and resource conservation, corrosion protection has been developed without using harmful heavy metal-based anticorrosion pigments such as chromium and lead. It has become necessary to develop water-based paints that provide coatings with excellent properties. In particular, it is strongly desired to improve the corrosion resistance on untreated iron surfaces that are not subjected to so-called chemical conversion treatments, as typified by zinc phosphate and iron phosphate coatings. In order to meet these demands, studies have been made to improve the performance of the resin itself without relying on anti-corrosion pigments, such as maleated polybutadiene resin, phenol-modified water-soluble resin, and ring-opened epoxy resin. Progress has been made in the development of water-based paints based on resins with excellent corrosion resistance, such as esterified epoxy-modified resins. [Problems to be Solved by the Invention] However, although the water-based paints described above are superior to water-based paints made mainly of unmodified, simple polyester resins and acrylic resins, they do not satisfy the recent demands for high anticorrosion performance. There was a problem that it was not possible. Attempts have also been made to add liquid epoxy resin emulsions to the various modified resins mentioned above, but these efforts have not been successful due to problems such as storage stability and poor finished appearance due to lack of compatibility. [Means for solving the problem] In view of the above-mentioned current situation, the present inventors conducted various research and found that a high molecular weight epoxy resin that is solid at room temperature exhibits extremely superior anti-corrosion properties compared to other resins. With this in mind, we investigated the application of this resin to water-based paints. As a result, we discovered that a special water-soluble epoxy-modified alkyd resin mainly composed of bisphenol-type epoxy resins exhibits good compatibility and excellent emulsifying ability with high-molecular-weight epoxy resins that are solid at room temperature. The present inventors have discovered that an aqueous dispersion paint containing a resin dispersion as a main component obtained by a combination of resins has excellent anti-corrosion properties, anti-storage stability, and good finished appearance, leading to the completion of the present invention. That is, the present invention includes the following component A and component B as coating film forming components, and component A/component B.
The main component is a resin dispersion with a 50% weight average particle diameter of 5 μm or less obtained by contacting a mixture with a weight ratio of 80/20 to 20/80 with water in the presence of a basic substance. This is an aqueous dispersion type coating composition. Component A: 30~bisphenol type epoxy resin
Contains 60% by weight in the resin main chain, has 10 to 35% by weight of alkyl groups having 8 to 30 carbon atoms in the resin side chain, and has an acid value.
10-40, hydroxyl value 100-300, number average molecular weight 1000-
10000 water soluble epoxy modified alkyd resin. Component B: Epoxy resin that is solid at room temperature, has a molecular weight of 2,000 to 30,000, and an epoxy equivalent of 1,500 or more. Component A in the present invention contains 30 to 60% by weight, preferably 30 to 50% by weight, of a bisphenol type epoxy resin in the resin main chain, and contains 10 to 30 carbon atoms, preferably 10 to 20 alkyl groups. ~35% by weight, preferably 10~30% by weight in the resin side chain, acid value 10~
40, preferably 15 to 30, hydroxyl value 100 to 300, preferably 100 to 200, number average molecular weight 1000 to 10000, preferably 1000 to 5000, and component B, which is a high molecular weight epoxy resin. It has complete compatibility with Component B, and has the effect of stably dispersing component B as fine particles in an aqueous medium and forming a coating film with high anticorrosion properties. As component A, a water-soluble epoxy-modified alkyd resin synthesized by a known method from a commercially available bisphenol type epoxy resin and a common polyester raw material can be used. As the bisphenol type epoxy resin component of the above raw material, a low molecular weight liquid epoxy resin is preferable because the modification reaction can be easily controlled. , Epicron 840, Epicron 850 (manufactured by Dainippon Ink & Chemicals Co., Ltd., trade name), Araldite
GY250, GY260 (manufactured by Ciba Geigy, product name)
etc. Examples of polyol components among the above polyester raw materials include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, hexanediol, 2,2-dimethylpentane-1,3-diol, and water. Examples include added bisphenol A, hexylene glycol, glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, trimethylolcyclohexane, pentaerythritol, sorbitol, diglycerol, dipentaerythritol, and the like. Examples of polybasic acid components include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, fumaric acid, succinic acid, glutaric acid, adipic acid, and trimethyladipine. acid, sebacic acid, dodecadicarboxylic acid, dimethylolpropionic acid, trimellitic anhydride, pyromellitic anhydride, butanetetracarboxylic acid, and the like. Examples of raw materials containing an alkyl group having 8 to 30 carbon atoms bonded to the resin side chain include fatty acids, 1
Examples include alcohols, fatty acid esters, and aliphatic epoxy compounds. Examples of fatty acids include soybean oil, coconut oil, safflower oil, cottonseed oil, rice bran oil,
Examples include natural fatty acids obtained from castor oil, dehydrated castor oil, hydrogenated castor oil, castor oil, linseed oil, tall oil, and various synthetic fatty acids of _C8 to _C30 . Examples of monohydric alcohols include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, and C ₈ to C ₃₀ synthetic alcohols obtained by reduction of the above-mentioned natural fatty acids;
Examples include _C2 to _C24 hydrogenated alkyl-substituted phenols. Examples of fatty acid esters include C _5
-C25 fatty acid glycidyl esters and aliphatic epoxy compounds include, for example, _C8 - _C30 α-
Examples include aliphatic epoxy compounds obtained by oxidation of olefins. The reason why component A is limited to the above range in the present invention is as follows. That is, if the content of the bisphenol type epoxy resin in the resin main chain of component A is less than 30% by weight, the compatibility with component B will be poor, and as a result, not only will a fine resin dispersion not be obtained.
When formed into a paint film, surface defects such as fading and wrinkles occur, and corrosion resistance is reduced. If it exceeds 60% by weight, the emulsifying power for component B will be insufficient, making it impossible to obtain a fine and stable resin dispersion, and the flexibility of the coating film will be impaired, which is undesirable. If the number of carbon atoms in the alkyl group in the resin side chain of component A is less than 8 or the content of the alkyl group is less than 10% by weight, the emulsifying power during emulsification may be insufficient and a stable and uniform resin dispersion may not be obtained. It is difficult to obtain, and when it is used as a paint, the surface tension becomes too high, making it difficult to wet and easily cause paint film defects such as repellency. In addition, if the number of carbon atoms in the alkyl group exceeds 30 or the content of the alkyl group exceeds 35% by weight, component B
This is not preferable because it impairs compatibility with the emulsifier and makes emulsification difficult. When the acid value of component A is less than 10, water solubility is insufficient and component B cannot be stably maintained in a dispersed state in the aqueous medium.
If it exceeds 40, not only the emulsifying power cannot be expected, but also the anticorrosion property when formed into a coating film decreases, which is not preferable. The hydroxyl value of component A is important for adjusting the solubility of component A in water, compatibility with component B, and as a crosslinking point when using a curing agent such as an aminoplast resin or a blocked isocyanate compound. If the hydroxyl value is less than 100, water solubility and compatibility with component B will be insufficient, making it impossible to obtain a stable resin dispersion, and when the above-mentioned curing agent is used, there will be too few crosslinking points, and If it exceeds 300, it is not preferable because it will adversely affect the anticorrosion properties and corrosion resistance of the coating film. In addition, if the number average molecular weight of component A is less than 1000, the emulsion stability of the protective colloid with respect to component B will be poor, it will be difficult to obtain a fine and stable resin dispersion, and the corrosion resistance and water resistance will be poor when formed into a coating film. , durability such as weather resistance is inferior and is not preferred. The number average molecular weight is
If it exceeds 10,000, it becomes difficult to mix during emulsification, the fluidity and smoothness of the coating film deteriorates during heat drying, and the solid content of the target coating composition decreases, which is undesirable. Component B in the present invention is an epoxy resin that is solid at room temperature, preferably has a melting point of 50 to 150°C, a molecular weight of 2000 to 30000, preferably 2000 to 10000, and an epoxy equivalent of 1500 or more, and is an aqueous resin of the present invention. It is a component that becomes finely emulsified in water as dispersed particles in a dispersed coating composition, and when it becomes a flying film, it provides excellent anticorrosion properties. As component B, commercially available epoxy resins that are solid at room temperature can be used as long as they satisfy the above range, such as Epicort 1007, Epicort 1009, Epicort 1100L (manufactured by Ciel Chemical Co., Ltd., trade name), Epiclon 7055, Epiclon 9055.
(manufactured by Dainippon Ink Chemical Co., Ltd., product name), Epotote YD017, Epotote YD019, Epotote YD020 (manufactured by Toto Kasei Co., Ltd.,
product name), etc. Furthermore, epoxy compounds and epoxy derivatives that can be easily produced by those skilled in the art from the above resins can also be used, such as fatty acid ester type epoxy resins, polyol type epoxy resins, polyglycol type epoxy resins, and the like. The reason why component B is limited to the above range in the present invention is as follows. That is, if component B is not solid at room temperature, the particles of the resin dispersion obtained tend to fuse, making it difficult to obtain a stable resin dispersion, which is not preferred. In addition, the molecular weight of component B is 2000
If it is below, not only will it not be possible to obtain a stable resin dispersion in a non-swelled state, but also the corrosion resistance and
Durability such as water resistance and alkali resistance is inferior,
If it exceeds 30,000, it is not preferable because it requires a lot of effort in the mixing operation during emulsification and the fluidity and smoothness of the coating film during heating drying is impaired. If the epoxy equivalent of component B is less than 1,500, the epoxy group will react excessively with the carboxyl group of component A during storage, resulting in significant thickening or gelation, which is undesirable. The aqueous dispersion type coating composition of the present invention contains the above-mentioned component A and component B in a weight ratio of 80/20 to 20/80, with most of component B and a part of component A forming fine particles in water. It is something that has grown and dispersed. At this time, the particle size of the dispersed particles mainly composed of component B is 5 μm.
It is desirable that the thickness is less than 5 μm, and if it exceeds 5 μm, the storage stability and the gloss value of the coating film will deteriorate, which is undesirable. The reason why the ratio of component A and component B is limited to the above range in the present invention is as follows. In other words, the amount of component A is the total amount of components A and B.
If it is less than 20%, the amount of particle components will be too large and a fine and stable resin dispersion cannot be obtained, resulting in poor smooth finish and storage stability. This is undesirable because the corrosion resistance of the paint decreases. The concentration of components A and B in the aqueous dispersion type coating composition of the present invention is preferably about 30 to 60% by weight in total. In addition to these essential components, the aqueous dispersion type coating composition of the present invention may contain other components as necessary, such as other water-soluble resins, pigments, curing agents, dryers, coating surface conditioners, etc. Good too. Since the coating composition containing component A and component B contains epoxy groups and carboxyl groups, a coating film can be formed even if it is baked as is, but it can be made into a thermosetting type by adding a curing agent or made into a forced drying type. is preferable. Examples of the curing agent include aminoplast resins and blocked isocyanates. In order to obtain a forced drying type, an unsaturated group is bonded to component A or component B, and a metal dryer is added as a catalyst. The aqueous dispersion type coating composition in the present invention has as its main component a resin dispersion obtained by contacting a mixture of the components A and B and other components added as necessary with water in the presence of a basic substance. It is something. Next, a method for producing a resin dispersion will be explained. In the present invention, components A and B are subjected to subsequent steps as a homogeneous mixture. At this time, the resin may be heated to aid mixing, and organic solvents commonly used in water-based paints may be used. Good too. For the former, it is preferable to keep the temperature at 140°C or lower in order to avoid reaction between the functional groups of component A and component B, and for the latter, the temperature should be adjusted to 140°C or lower in order to avoid impairing the properties of the water-based paint. 40% by weight or less is desirable. In the present invention, the resin mixture is then neutralized with a basic substance, and the basic substances used at this time can be those commonly used in water-based paints, such as ammonia, triethylamine, dimethylethanolamine, etc. , diethylmethanolamine, diethanolamine, methyldiethanolamine, 2-amino-2-methylpropanol, and the like. The neutralization rate of these basic substances for carboxyl groups in the resin mixture is 0.2~
It is preferably within the range of 1 molar equivalent; if it is less than 0.2 molar equivalent, the dispersed particles cannot be stably emulsified, and if it exceeds 1 molar equivalent, the viscosity of the resin dispersion increases and the solid content of the target coating material is increased. This is undesirable because it causes a decrease in The resin mixture neutralized with the above basic substance is then subjected to an emulsification process in an aqueous medium, but in order to obtain a fine resin dispersion with a uniform particle size distribution and within the above particle size range, the above-mentioned Most preferred is an emulsification method in which water is continuously added to the resin mixture. At this time, the resin mixture and the water to be added may be heated in advance for the purpose of aiding dispersion in the aqueous medium.
The amount of water brought into contact with the resin mixture is preferably about 40 to 200% by weight based on the weight of the resin mixture. Furthermore, if a water-insoluble curing agent is desired to be used in the intended final coating composition, the curing agent may be mixed in advance with the resin mixture and dispersed in the aqueous medium in this emulsification step. For stirring and mixing in the emulsification step, a stirrer commonly used in the paint industry can be used. The particle size of the resin dispersion produced by the above emulsification method is determined by the emulsifying ability of component A, which acts as a polymeric surfactant, with respect to component B.
The particle size of the resulting resin dispersion can be controlled by changing the amount of component A in the resin mixture during emulsification and the neutralization ratio of the basic substance to the carboxyl groups in the resin mixture. The resin dispersion obtained as described above is mixed with other components added as necessary, such as other water-soluble resins, curing agents, dryers, coating surface conditioners, etc., to form an aqueous dispersion paint by a known method. It can be a thing. In addition, in the case of preparing a pigmented aqueous dispersion coating composition, it is possible to prepare a pigment paste by a conventional method using a part of component A and mix it with a resin slurry, or furthermore, to prepare a pigment paste in advance into a resin mixture. It can be manufactured by any method such as kneading a pigment in advance and manufacturing a pigment-containing resin dispersion. [Function] The aqueous dispersion type coating composition produced as described above is applied to the object to be coated in the same manner as conventional aqueous dispersion type paints, and a coating film is formed by natural drying, baking curing, forced drying, etc. The aqueous dispersion type coating composition of the present invention has a water-soluble epoxy-modified alkyd resin with excellent corrosion resistance and a high molecular weight epoxy resin as main film-forming components, and therefore provides a coating film with high corrosion resistance. In addition, since the water-soluble epoxy-modified alkyd resin acts as a polymeric surfactant for the high-molecular weight epoxy resin, the dispersed particles maintain a stable dispersion state.
Excellent storage stability. Furthermore, the resin dispersion constituting the aqueous dispersion type coating composition of the present invention consists of fine particles with a size of 5 μm or less, and the water-soluble resin and particle resin have perfect compatibility, resulting in a good finished appearance. have [Effects of the Invention] As described above, according to the aqueous dispersion type coating composition of the present invention, the high molecular weight epoxy resin with high corrosion resistance is
Because it is dispersed as fine particles in an aqueous medium containing a specific water-soluble resin, it has excellent corrosion resistance, storage stability, and finished appearance. [Examples] Next, production examples, examples, comparative examples, and test examples of the present invention will be described. In each example, parts are parts by weight,
% indicates weight %. Production example 1 Production of component A ₁ In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, add 13.54 parts of lauric acid, 21.76 parts of adipic acid, and Epicote 828.
(manufactured by Ciel Chemical Co., Ltd., trade name, hereinafter the same) was charged, and the temperature was raised to 120°C in 30 minutes. When the temperature reached 120°C, 0.05 part of dimethylethanolamine was added, and the reaction was continued at 140°C for 2 hours. Then 4.51 parts of trimellitic anhydride, neopentyl glycol
7.95 parts of trimethylolpropane and 6.42 parts of trimethylolpropane were charged, the temperature was raised to 180°C in 1 hour, and the esterification reaction was continued at the same temperature for 2 hours to obtain a reaction product with an acid value of 30. After cooling this reaction product to 120°C,
Dilute with 9.66 parts of 3-methoxy-3-methylbutanol (Solfit, manufactured by Kuraray Co., Ltd., trade name, hereinafter the same) to give an epoxy resin content of 40%, a lauric acid content of 15%, a resin acid value of 30, and a hydroxyl value. A water-soluble epoxy-modified alkyd resin _A1 having a molecular weight of 180, a number average molecular weight of 1400, and a solid content of 90% was obtained. Production Example 2 Production of Component A ₂ In a flask similar to Production Example 1, add 27.05 parts of Hi-Diene (manufactured by Soken Kagaku Co., Ltd., trade name, C ₁₈ unsaturated fatty acid, the same hereinafter), 14.42 parts of adipic acid, and Epicoat.
36.06 parts of 828 (mentioned above) were charged, and the temperature was raised to 120°C in 30 minutes. When the temperature reached the same temperature, 0.05 part of dimethylethanolamine was added, and the reaction was continued at 140°C for 2 hours. Next, 4.52 parts of trimellitic anhydride, 0.45 parts of neopentyl glycol, and 7.66 parts of trimethylolpropane were charged, the temperature was raised to 180°C in 1 hour, and the esterification reaction was continued at the same temperature for 1.5 hours to form a reaction product with an acid value of 30. I got it. This reaction product is 120
After cooling to ℃, diluted with 9.79 parts of 3-methoxy-3-methylbutanol to obtain an epoxy resin content of 40%, _C18 fatty acid content of 30%, resin acid value of 30, hydroxyl value of 140, number average molecular weight of 1750, solid. A 90% water-soluble epoxy modified alkyd resin _A2 was obtained. Production Example 3 Production of Component A ₃ In a flask similar to Production Example 1, add 15.88% of lauric acid.
part, adipic acid 21.48 parts, Epicote 828 (supra)
Add 36.09 parts of dimethylethanolamine and raise the temperature to 120℃ in 30 minutes.
0.05 part was added, and the reaction was continued at 140°C for 2 hours.
Next, 4.52 parts of trimellitic anhydride and 12.27 parts of trimethylolpropane were charged, the temperature was raised to 180°C over 1 hour, and the esterification reaction was continued at the same temperature for 1.5 hours to obtain a reaction product with an acid value of 50. After cooling this reaction product to 120°C, 3-methoxy-3-
Diluted with 9.71 parts of methylbutanol, epoxy content 40%, lauric acid content 17.5%, resin acid value.
50, a water-soluble epoxy-modified alkyd resin _A3 having a hydroxyl value of 180 and a number average molecular weight of 1,400 was obtained. Production Example 4 Production of Component B ₁ In a flask similar to Production Example 1, add 27.10 parts of xylene.
63.24 parts of Epicote 1007 (manufactured by Ciel Kagaku Co., Ltd., trade name, molecular weight 2900, epoxy equivalent weight 1850, hereinafter the same) and 9.57 parts of Hi-Diene (described above) were charged and heated to 130°C. After confirming that Epicote 1007 was completely dissolved, 0.09 part of dimethylethanolamine was added and the reaction was continued at the same temperature for 2 hours. After the reaction is complete,
Remove xylene under reduced pressure and reduce the molecular weight in solid form at room temperature.
3500, 100% solid content with epoxy equivalent over 2000
A fatty acid ester epoxy resin was obtained. Example 1 32.16 parts of water-soluble epoxy-modified alkyd resin _A1 ,
15.59 parts of Epicote 1007 (mentioned above) and 5.45 parts of methylpropylene glycol were heated and mixed at 120°C to obtain a uniform resin mixture. Next, the temperature of this resin mixture was lowered to 70°C, and while stirring with a homodisper (manufactured by Tokushu Kika Kogyo Co., Ltd., hereinafter the same), 0.88 parts of dimethylethanolamine corresponding to 0.65 molar equivalent of carboxyl groups in the resin mixture was added. After homogeneous neutralization, 45.92 parts of deionized water was gradually added over 1 hour while maintaining the same temperature. After adding deionized water, cool with cold water, solids content 47.5%, component A ₁ and component B.
(Epicote 1007) in a ratio of 65/35 was obtained. When the particle size of this resin dispersion was measured using a particle size distribution analyzer, the 50% weight average particle size was 0.3 μm. Next, in order to produce a black aqueous dispersion type coating composition from the resin dispersion, first, water with a solid content of 35% consisting of 38.89 parts of water-soluble epoxy-modified alkyd resin A ₁ , 1.25 parts of dimethylethanolamine, and 59.86 parts of deionized water was prepared. An aqueous resin solution of a soluble epoxy-modified alkyd resin was obtained. Then, the above resin aqueous solution
A black paste was prepared by dispersing in a sand mill for 1 hour at a mixing ratio of 51.87 parts, precipitated barium sulfate, 36.32 parts, carbon black, 7.27 parts, and deionized 4.54 parts. 22.34 parts of this black paste, 69.27 parts of the above resin dispersion, 4.11 parts of water-soluble melamine resin (Cymel #303, manufactured by Mitsui Toatsu Chemical Co., Ltd., hereinafter the same name) as a crosslinking agent, 0.17 parts of dimethylethanolamine
1 part, 0.16 parts of paratoluenesulfonic acid, 0.10 parts of an additive for water-based paints (Agitol A black water-based dispersion paint was obtained in which the ratio of resin components was 2.4/10 and the ratio of water-soluble epoxy modified alkyd resin A ₁ to Epicote 1007 was 70/30. Example 2 29.03 parts of water-soluble epoxy-modified alkyd resin _A1 ,
Epicote 1009 (manufactured by Ciel Chemical Co., Ltd., trade name, molecular weight 3750, epoxy equivalent weight 2850, hereinafter the same) 21.38 parts,
7.52 parts of methylpropylene glycol was heated and mixed at 120°C to obtain a homogeneous resin mixture. Next, the temperature of this resin mixture was lowered to 80°C, and while stirring with a homodisper, 0.81 part of dimethylethanolamine, which corresponds to 0.65 molar equivalent of carboxyl groups in the resin mixture, was added to uniformly neutralize it, and while maintaining the same temperature. , 41.26 parts of deionized water was gradually added over 1 hour. After the addition of deionized water was completed, the mixture was cooled with cold water to obtain a resin dispersion having a solid content of 47.5% and a ratio of Component A ₁ to Component B (Epicote 1009) of 55/45.
When the particle size of this resin dispersion was measured using a particle size distribution analyzer, the 50% weight average particle size was 0.6 μm. Next, 71.32 parts of the above resin dispersion, 23.00 parts of the black paste prepared in Example 1, 4.23 parts of water-soluble melamine resin, 0.14 parts of dimethylethanolamine, 0.16 parts of para-toluenesulfonic acid, and 0.10 parts of the additive for water-based paints. Furthermore, 1.03 parts of deionized water was added to achieve a solids content of 53% and a pigment to resin ratio of 2.4/
10. A black water-based dispersion paint containing water-soluble epoxy-modified alkyd resin A ₁ and Epicoat 1009 in a ratio of 60/40 was obtained. Example 3 32.50 parts of water-soluble epoxy-modified alkyd resin _A2 ,
15.75 parts of solid fatty acid ester epoxy resin B ₁ ,
4.69 parts of methylpropylene glycol was heated and mixed at 100°C to obtain a homogeneous resin mixture. Next, the temperature of this resin mixture was lowered to 60°C, and while stirring with a homodisper, 1.18 parts of triethylamine, which corresponds to 0.75 molar equivalents of carboxyl groups in the resin mixture, was added to uniformly neutralize it, and while maintaining the same temperature, it was desorbed. 45.88 parts of ionized water was gradually added over 1 hour. After adding deionized water, cool with cold water.
A resin dispersion with a solid content of 45% and a ratio of component A ₂ to component B ₁ of 65/35 was obtained. When the particle size of this resin dispersion was measured using a particle size distribution analyzer, the 50% weight average particle size was 0.5 μm. Next, in order to produce a black aqueous dispersion type coating composition from the above resin dispersion, 18.52 parts of water-soluble epoxy-modified alkyd resin A ₂ , 0.77 parts of triethylamine,
28.33 parts deionized water, 33.33 parts precipitated barium sulfate
1 part and 6.67 parts of carbon black were dispersed in a sand mill for 1 hour based on the mixing ratio to prepare a black paste. Next, 22.20 parts of this black paste, 74.68 parts of the above resin dispersion, 0.08 parts of triethylamine, and 1.49 parts of a 2.5% manganese naphthenate solution as a dryer.
1.49 parts of 2.5% cobalt naphthenate solution, 0.10 parts of water-based paint additive, solid content 46.3%, pigment to resin ratio 2.4/10, water-soluble epoxy modified alkyd resin A ₂ and solid fatty acid. A forced dry black water-based dispersion paint with an ester epoxy resin B ₁ ratio of 70/30 was obtained. Comparative Example 1 Water-soluble epoxy-modified alkyd resin _A1 , which is an epoxy-modified resin obtained by ring-opening esterification of the bisphenol-type epoxy resin used in Example 1, was used, and compared to Example 1, Epicoat, which is a particle component, was used.
A water-soluble coating composition containing no 1007 was produced. That is, 75.39 parts of the resin aqueous solution of the water-soluble epoxy-modified alkyd resin _A1 obtained in Example 1, 19.10 parts of the same black paste, and the water-soluble melamine resin.
5.28 parts, 0.13 parts of para-toluene sulfonic acid, and 0.10 parts of additive for water-based paints to make the solid content 43.6.
%, pigment to resin ratio 2.4/10, water-soluble epoxy modified alkyd resin A ₁ and Epicote 1007
A black water-soluble paint having a ratio of 100/0 was obtained. Comparative Example 2 An aqueous dispersion type coating composition was produced using a water-soluble epoxy-modified alkyd resin _A3 having a higher acid value than the water-soluble epoxy-modified alkyd resin _A1 used in Example 1. That is, by changing the water-soluble epoxy-modified alkyd resin A ₁ in Example 1 to water-soluble epoxy-modified alkyd resin A ₃ , and using the same blending ratio and operating procedure, the solid content was 51.5% and the ratio of pigment to resin was
2.4/10, water-soluble epoxy modified alkyd resin A ₃
A black water-based dispersion paint with a ratio of 70/30 of 1007 and Epicote 1007 was obtained. Comparative Example 3 Epicote, component B used in Example 1
Epicote 1001 (manufactured by Ciel Chemical Co., Ltd., trade name, molecular weight) has a lower molecular weight and epoxy equivalent than 1007.
900, epoxy equivalent: 500) to produce an aqueous dispersion type coating composition. That is, by replacing Epicote 1007 in Example 1 with Epicote 1001 and using the same blending ratio and operating procedure, the solid content was 51.5% and the ratio of pigment to resin was
2.4/10, water-soluble epoxy modified alkyd resin A ₁
A black water-based dispersion paint with a ratio of 70/30 of 1001 and Epicoat 1001 was obtained. Test Example The black paint composition prepared in each of the above Examples and Comparative Examples was diluted with deionized water, and the diluted paint was applied to a degreased dull steel plate for 25 seconds at a food #4 viscosity (20°C). Air spray coating was applied to a film thickness of 30 μm, set at 20°C for 10 minutes, then set at 60°C for 5 minutes, and then baked at 140°C for 30 minutes to obtain a finished coating. The physical properties and corrosion resistance of the coating film were tested. Furthermore, the storage stability performance of the coating compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was determined after storing them at room temperature for one month. The results are shown in Table 1.

[Table] From the above results, Examples 1 to 3 were excellent in corrosion resistance, finished appearance, and storage stability. In comparison, Comparative Example 1 did not contain a solid high molecular weight epoxy resin, and therefore could not provide high corrosion resistance.
In addition, because Comparative Example 2 used a water-soluble epoxy-modified alkyd resin with a high acid value, and Comparative Example 3 used an epoxy resin with a low molecular weight and small epoxy equivalent as a particle component, both had poor corrosion resistance and storage stability. Ta.

Claims (1)

[Claims] 1. A mixture containing the following components A and B as coating film forming components and having a component A/component B (weight ratio) of 80/20 to 20/80 is mixed with water in the presence of a basic substance. An aqueous dispersion type coating composition characterized in that it contains as a main component a resin dispersion having a 50% weight average particle diameter of 5 μm or less obtained by contacting with a resin dispersion. Component A: 30~bisphenol type epoxy resin
Contains 60% by weight in the resin main chain, has 10 to 35% by weight of alkyl groups having 8 to 30 carbon atoms in the resin side chain, and has an acid value.
10-40, hydroxyl value 100-300, number average molecular weight 1000-
10000 water soluble epoxy modified alkyd resin. Component B: Epoxy resin that is solid at room temperature, has a molecular weight of 2,000 to 30,000, and an epoxy equivalent of 1,500 or more. 2. Claim 1, wherein component A is a water-soluble epoxy-modified alkyd resin synthesized from a bisphenol type epoxy resin and a polyester raw material.
The aqueous dispersion type coating composition described in . 3 The polyester raw material has 8 to 30 carbon atoms bonded to the polyol component, polybasic acid component, and resin side chain.
The aqueous dispersion type coating composition according to claim 2, which is an alkyl group raw material. 4. The aqueous dispersion type coating composition according to claim 3, wherein the alkyl group material having 8 to 30 carbon atoms bonded to the resin side chain is a fatty acid, a monohydric alcohol, a fatty acid ester, or an aliphatic epoxy compound.